Newer diarrheal syndromes

Aetiological diagnosis of protracted diarrhoea remains obscure in as many as 30% of cases despite extensive investigations. A number of newer syndromes have been recognized amongst this "idiopathic group" which includes microvillous inclusion disease, "tufting" enteropathy and epithelial dysplasia, autoimmune enteropathy and "syndromic" immunodeficiency with characteristic facial abnormalities, woolly hair and intractable diarrhea. The molecular basis of some of these syndromes has been reviewed but in only a small series of patients has the functional defect been characterized. If a case is suspected the antenatal history, family history and history of consanguinity should be sought. Extra-intestinal manifestations, presence of gut or other auto-antibodies, together with phenotypic abnormalities should be looked for. Careful light and electron microscopy is done of small bowel biopsies, although microvillous inclusion disease can be usually suspected on PAS staining. Large bowel biopsy may be needed to exclude an unsuspected microscopic colitis. The prognosis of this group of conditions is poor with an overall 50-85% mortality. Although successful gut transplantation has been reported, genetic counselling may be one of the more important aspects of the clinicians' role.